. >>> cia director david petraeus resigns after admitting to cheating on his wife of 38 years, more on the fbi investigation that exposed the allege ad fair with his biographer -- alled affair with his biographer. >> the fiscal cliff countdown, president obama warns congress act or else the united states will see tax hikes, job losses, even a double dip recession. >> new information about a teenager accused of beating and robbing an elderly woman, what helped police track him down and what he told detectives after his arrest. thanks for joining us tonight. i'm shawn yancy. >> i'm will thomas. >>> we begin with david petraeus stepping down in disgrace. >> fox news has learned the cia director resigned after an fbi investigation revealed the retired four star general was having an fair with his biographer. fox 5's maureen umeh has the story. >> paula broadwell wrote general petraeus' biography. initially the fbi thought petraeus may have been a victim but so far there's been no evidence to back up that concern. cia director general david petraeus step down after 14 months on the job offe